Examples of a radiation detector that detects radiation such as γ-rays include one whose appearance is illustrated in FIG. 20. Such a radiation detector 51 includes a scintillator 52 having scintillation counter crystals c being arranged three-dimensionally in vertical, horizontal, and height directions, and a light detector 53 that detects fluorescence emitted from the scintillator 52. The fluorescence generated from the scintillator 52 is obtained by converting radiation (see, for example, Patent Literature 1).
The radiation detector 51 has a function of discriminating a part of the scintillator 52 in which fluorescence is emitted when determining the fluorescence. Such a function is called a fluorescence position discriminating function. The radiation detector 51 discriminates a position of fluorescence by identifying which of the scintillation counter crystals c constituting the scintillator 52 emits fluorescence.
Accordingly, the scintillator 52 having the simply arranged scintillation counter crystals c allows no accurate position discrimination of the fluorescence. Specifically, discriminating which of the crystals arranged in a height direction with hatch patterns in FIG. 20 emits fluorescence requires reflectors 54 each provided in a gap between adjacent crystals constituting the scintillator 52 for reflecting fluorescence.
The following describes a configuration of the reflectors 54. The reflectors 54 each have the same height as the crystal, and include two types that extend horizontally and vertically, respectively. The reflector 54 extending horizontally engages the reflector 54 extending vertically, whereby a reflector frame is formed having the reflectors 54 in a grid manner. The crystals are arranged so as to be fitted into the reflector frame.
Another scintillator 52 with a new configuration has been currently developed. Specifically, as illustrated in FIG. 21, the scintillator 52 has been developed in which the scintillation counter crystal c of FIG. 20 are integrated in the height direction. Such a scintillator 52 achieves enhanced sensitivity of the radiation detector 51. That is, the scintillator 52 of FIG. 21 positively allows the fluorescence to reach the light detector 53, which configuration differs from that in FIG. 20 with four scintillation counter crystal layers (see, for example, Patent Literature 2).
The scintillator 52 having the configuration illustrated in FIG. 21 also includes four reflector frames constituted by the reflectors 54. The reflector frames allow the radiation detector 51 to discriminate generating positions of the fluorescence in the height direction.
Patent Literature 1: Japanese Patent Publication No. 2004-279057A
Patent Literature 2: International Publication No. WO2009/101730A